The present invention is directed to an autostereoscopic display and method of displaying multidimensional images on the display. More particularly, the autostereoscopic display of the present invention includes a lenslet array of rotated cylindrical lenses positioned between a viewer and a pixel array. The present invention allows the interlacing of multiple image views by using segmented lenslets. The use of grayscale technology controls the lenslet shape and rotation very precisely to control the blurring and blending of views. An autostereoscopic display in accordance with the present invention is particularly advantageous for creating stereoscopic displays in conjunction with color pixel arrays.
Conventionally, three-dimensional displays of images have been achieved by using stereoscopic displays. A stereoscopic display is a display providing multidimensional image cues to a viewer by combining two alternative two-dimensional views of the same object or scene. Each view is observed by one of the viewer""s eyes and the two views are subsequently integrated by the human visual system to form a three-dimensional (3-D) image as perceived by the viewer, through the display.
A simple example of an autostereoscopic display is the classic 3-D image and accompanying 3-D glasses used to view the image. The 3-D image contains superimposed red and green images slightly offset from each other and independently representing an object from separate, slightly different perspectives. The overlapped red and green images are integrated when a viewer wearing glasses with a red-color filter over one eye and a green-color filter over the other eye views the image and the respective perspectives are directed independently to the respective eyes receiving the image information. The result observed by the viewer is that the image appears to have a limited amount of spatial depth.
There are problems associated with using these types of 3-D glasses. First, they are usually flimsy and bulky and not well suited for ordinary wear. Furthermore, subjects that are residing in the images when viewed without the 3-D glasses are not easily discerned. Also, they do not interface well with individuals who need to wear corrective lenses.
To address such aforementioned problems and disadvantages, it is desirable to have autostereoscopic displays requiring no special glasses or other type of head-mounted equipment to bring the alternative views to each of the viewer""s eyes. In one example, conventional autostereoscopic displays have been implemented on an LED display, by alternately generating light emitting lines on the display representing interlaced left and right eye images and respectively directing the interlaced left and right images to a viewer""s left and right eyes. Such an implementation may require construction of a specialized flat panel display and/or display driver incorporating the capability to generate the light emitting xe2x80x9clinesxe2x80x9d or interlaced images. This type of display would be capable of replacing conventional backlit display sources.
Other conventional autostereoscopic displays have been proposed with lenses positioned in alignment with display picture elements. However, there are problems arising with this approach, because the interlaced left and right eye images directed at fixed viewing angles do not necessarily represent a viewer""s actual left eye and right eye viewing zones. Further, such an implementation may also require construction of a specialized flat-panel display incorporating cylindrical lenses embedded within the display picture elements structure. Also, because such lenses are aligned, interference pattern noise or moire patterns may result from spatial mismatches between pixel edges and cylindrical lens edges when viewed off-axis. Such alignment may further result in projection of images outside the viewer""s proper left and right eye viewing zones. Additional problems may arise when one attempts to implement autostereoscopic display on color displays.
Color displays are normally constructed with pixels having a plurality of color elements such as red, green, and blue arranged alongside each other along a generally horizontal line of the display relative to a position of intended use. Another common characteristic of conventional displays is that the color elements associated with the pixels tend to be vertically aligned so that, for example, red, green, and blue elements are vertically aligned with each other throughout the display. In this case, problems arise in displaying color images in such a situation since the focal axis of a typical lens is vertical and thus the point focus in a color display where color elements are vertically aligned would be on only one color at a time, thereby distorting the color rendering for the image.
Consequently, in order to create an autostereoscopic color display which accurately renders color, the display should be rotated ninety degrees or otherwise physically altered to achieve a change in orientation, so that the color elements of the pixels are arranged vertically one above the other. Color elements of pixels are then appropriately oriented with respect to the vertical focal axis of the lens. It should be noted that rotating or otherwise physically altering the display may require modification to any software drivers that support the display. Thus, the extent to which existing or conventional displays may be adapted to provide stereoscopic images is limited, because of this rotation and other such alterations required of the display.
For a better understanding of the characteristics of known systems, reference is made to an exemplary autostereoscopic display as shown in FIG. 1A. Included is a pixel array 11, having several pixel groups 111. These pixel groups typically include three color elements such as red, green, and blue (RGB). A lenticular array 12 is positioned adjacent to pixel array 11 separated by a distance xe2x80x9cdxe2x80x9d which varies based on the desired or anticipated distance S between a viewing perspective represented in FIG. 1A as, for example, eyes 13-14 [left eye (13) and right eye (14)] and the front of the autostereoscopic display. As will be understood by one skilled in the art, each pixel group 111 includes pixel columns corresponding to independent image perspectives which, when viewed together form the autostereoscopic display image.
In accordance with the autostereoscopic display illustrated in FIG. 1A, lenticular array 12 includes several adjacent lenses, each lens 121-123 within lenticular array 12 corresponding to different pixel columns 112-113 within the pixel groups 111 of the pixel array 11. By anticipating both the distance S between a viewer and the lenticular array 12 located at the front of the pixel array 11 and the desired separation xe2x80x9cdxe2x80x9d between pixel lens arrays 11 and 12, an appropriate pitch WL for lenses 121-123 within a lenticular array of the display may be calculated (described later in greater detail) such that the autostereoscopic effect is achieved. A desired separation d between the pixel and lenticular arrays 11 and 12 may be determined based on various criteria, such as the size and/or appearance of the resulting display. Typically, the separation d is representative of the focal length of the lenses that are used to make up the lenticular array.
Further, reference is made to an exemplary autostereoscopic display as illustrated in FIG. 1B. It should be noted that due to the similarity between FIG. 1A and FIG. 1B, the reference numerals shown in FIG. 1B and the accompanying discussion herein below relate to aspects of the display which differ from those aspects already illustrated in FIG. 1A.
The displays shown in FIGS. 1A and 1B differ with respect to the alignment of the lenses within lenticular array 12 relative to the pixel groups 111 within pixel array 11. FIG. 1B illustrates a configuration in which the position of the lenticular array 12 is shifted slightly from the position shown in FIG. 1A relative to pixel array 11, or alternatively, the viewing position is shifted. Specifically, in FIG. 1B, the center of lens 124 within lenticular array 12 is aligned with the center of pixel group 111xe2x80x2 within pixel array 11 with respect to the long axis of the cylindrical lenses within lenticular array 12. In FIG. 1B, this alignment is achieved at eye bisector 15. The bisector is a line which bisects the distance between the left eye 13 and the right eye 14 of the viewing observer.
This alignment is preferably achieved at a point which is the center of the autostereoscopic display. Because of this alignment, the lenses 124-126 of FIG. 1B, each correspond to pixel columns 112-113 within a single pixel group 111 or 111xe2x80x2, in contrast with the lenses of FIG. 1A which each correspond to pixel columns 112-113 in different pixel groups 111. Nevertheless, the pitch WL of lenses 124 and 126 remains smaller than the pitch 2WP of corresponding pixel columns 111 and 111xe2x80x2, such that lenses 125-126 other than central lens 124 are offset from their corresponding pixel columns 111 with respect to the long axis of cylindrical lens within lenticular array 12. Therefore, for reasons similar to those discussed above, the offset between the center of lenses 125-126 and their corresponding pixel columns 111 increases as the distance from central lens 124 increases. Such offsets are desirable for independent viewing of right and left interlaced image xe2x80x9cslicesxe2x80x9d by respective right and left eyes as will be described in greater detail later.
FIG. 2A illustrates a front view of a portion of a pixel array arranged to simultaneously display two views of an image to enable an autostereoscopic display. FIG. 2A-1 shows that pixel columns 112 and 113 are configured to display color images, shown, for example, as having R,G,B color elements. It should further be noted that due to conventional methods of construction, R,G, and B color elements are typically vertically aligned leading to particular disadvantages associated with retrofitting such conventional displays for autostereoscopic display. As can be seen in FIG. 2B, left and right view information may be arranged on pixel array 11, so that images directed toward the left eye 13 and images directed toward the right eye 14 are interlaced. Thus, images intended to be viewed by the left and right eye are displayed on alternating pixel columns 112, 113 within the pixel array 11. Note that although pixel array 11 includes several pixel columns, a sample of only four pixel columns from within pixel array 11 is illustrated in FIGS. 2A and 2B. It should be further noted that while the disadvantages are described with reference to color elements including R,G, and B, typical displays may contain more green color elements per line than other displays. A typical ratio of two green elements to every one red element and one blue element is represented by the ratio 2G:1R:1B.
As previously described, pixel array 11 includes several pixel columns arranged in parallel to the longitudinal axis of cylindrical lenses within lenticular lens array 12. Lenses are preferably arranged such that left eye 13 perceives an image created by visually joining all pixel columns 112 associated with a left eye image, designated in FIG. 2A by dark shading. Right eye 14 preferably perceives an image created by visually joining all pixel columns 113 associated with a right eye image, designated in FIG. 2A by diagonal lines. It should be noted that the resolution achieved by a stereoscopic device is related to the number of pixel columns found in the display and the number of pixel columns per pixel group. A flat screen display with P pixel columns that each have Q pixels has a non-autostereoscopic image resolution of Pxc3x97Q pixels. By contrast, the same flat screen display has an autostereoscopic image resolution equal to P*Q/n pixels, assuming n views in the autostereoscopic display. As an example, in the exemplary systems illustrated in FIGS. 1A through 2B, the image resolution would be P*Q/2 pixels, since each pixel group 111 has two (2) pixel columns 112-113 to achieve two (2) separate views.
However, disadvantages occur where color elements are vertically aligned, because the focus of a cylindrical lens may fall on only one color element of an associated pixel column. It will be appreciated that in order to view a relatively natural undistorted color representation of an image, all color elements of an associated pixel must be viewed. Some systems have addressed this problem by rotating the display 90 degrees or by using more than one lenticular layer of lenses. Both of these solutions are relatively difficult to use. For example, a lenticular mask or overlay layer over a conventional display used in a conventional manner to achieve an autostereoscopic display.
Therefore, it would be desirable to provide a method of providing an autostereoscopic display capability particularly suitable for color displays. Such a method and associated apparatus would preferably allow the use of a conventional display having a pixel array and color elements associated with each of the pixels. The present invention also addresses the problems mentioned previously, as well as the ability to eliminate or minimize the effect of unwanted visual artifacts (such as blacklines) and improving the interlacing of multiple images.
Other and further objects, features and advantages of the present invention will be set forth in the description that follows, and in part, will become apparent from the detailed description, or may be learned by practice of the invention.
To address the disadvantages posed in adapting conventional displays to provide autostereoscopic display, a method and apparatus are described in accordance with various exemplary embodiments of the present invention for supplying a stereoscopic image when a display is viewed from an intended viewing perspective. A pixel array associated with the display may include a plurality of pixels, each having at least two subpixel elements, e.g. color elements, the pixels extending in a generally horizontal direction from the intended viewing perspective. A lenslet array including a plurality of lenses may be positioned between the intended viewing perspective and the pixel array, and may further be configured to transpose a focus orientation associated with the subpixels from a generally vertical orientation to a generally horizontal orientation such that the subpixel elements are brought within the transposed focus orientation which is generally diagonal. By transposing the focal orientations in such a manner, all color elements associated with a pixel are brought into focus despite vertical alignment of color subpixel elements. Thus each pixel in the pixel array is focused by a corresponding one of the plurality of lenses although the correspondence of pixels to lenses is preferably two pixels for each microlens or lens element in the lenslet array. Thus the lenslet array includes a plurality of rotated cylindrical lenses having a generally diagonal focus. Each of the pixels has at least three subpixel elements, including a red subpixel element, a green subpixel element and a blue subpixel element.
In accordance with alternative exemplary embodiments of the present invention, an autostereoscopic display is provided with a pixel array including a plurality of pixel groups and a lenslet array positioned between the pixel array and a viewing perspective. It should be noted that the lenslet array is configured to transpose a focus orientation and includes a plurality of lenses corresponding generally to a plurality of pixels of the pixel array such that such that each of the plurality of lenses of the lenslet array corresponds to each of the pixel groups. One exemplary number of pixels associated with the pixel group is two (e.g. each lens corresponds to two pixels) with the orientation of the two pixels being side by side. It should further be noted that the plurality of pixels include a plurality of color pixels and each of the color pixels includes at least two color components arranged in a first direction, e.g. generally horizontal with respect to the normal physical orientation of the display (also horizontal), and lenses of the lenslet array are preferably rotated cylindrical lenses having a transposed focal axis from around a second direction, e.g. vertical, to the first direction generally perpendicular to the second direction. Note that the orientation directions of horizontal and vertical are usually given with respect to the eyes that are viewing the display, although other frames or reference can be used without departing from the scope and spirit of the present invention.
Further, in accordance with alternative exemplary embodiments of the present invention, each of the pixels includes at least two color components arranged in a horizontal direction with respect to the display, and the plurality of lenses of the first array comprise rotated cylindrical lenses having a transposed axis extending from around a vertical direction to around the horizontal direction with respect to the display according to an arbitrary axis of rotation.
In another exemplary embodiment a autostereoscopic display for supplying a stereoscopic image when viewed from an intended viewing perspective includes a lenslet array including a plurality of lens elements. A cylindrical axis runs down the center of each lens element in the lenslet array and wherein the cylindrical axis can be tilted at an angle that is dependent upon a layout and an orientation of a plurality of display pixels of the autostereoscopic display. The cylindrical axis can be tilted at an angle between 5 and 55 degrees. An image formed on the display pixels implements a black line removal process by blurring and rotating an image. The blurring and rotating of the image is performed in accordance with an established blurring and rotating value. The lenslet array used can be a lenslet array. The lens element used can be a microlens element.
In another exemplary embodiment, a method of displaying multidimensional images on an autostereoscopic display includes establishing a lenslet array to include a plurality of lens elements. There is an interlacing of a plurality of multiple images on the display with a fanning of the multiple images out into an angular array. The method establishes a plurality of views in a vertical and horizontal direction. A mapping of a plurality of views onto a plurality of pixels making up the display and a three dimensional image is generated from the fanned out multiple images.
The method further includes establishing a lenslet array including a plurality of lens elements; using a cylindrical axis running down the center of each lens element in the lenslet array. The cylindrical axis can be tilted at an angle that is dependent upon a layout and an orientation of a plurality of display pixels of the autostereoscopic display. The cylindrical axis can be tilted at an angle between 5 and 55 degrees. An image formed on the display pixels implements a black line removal process by blurring and rotating an image. The blurring and rotating of the image is performed in accordance with an established blurring and rotating value.